As cichlid keepers, we’re all aware of aggression and the typical behavioral scenarios that promote it. Breeding, offspring defense, territory defense, and food competition are the main ones. And though we naturally associate these behaviors with adult or adolescent fish, fry exhibit aggression too.
A recent study published in the latest issue of Hydrobiologia shows aggression can begin very early in a cichlid’s life. In an experiment involving fry of Neolamprologus furcifer from Lake Tanganyika, it was discovered that early-stage fry (as young as ~2 weeks old) demonstrate sibling aggression. The study focused on the fry as they fed on small atyid shrimp. Most (frequency) aggression was observed among the fry between the ages of 4 and 6 weeks. While the severity of the aggression was not specifically tested, it was noted that the sibling aggression was non-lethal.
The study was performed in situ (meaning in Lake Tanganyika itself rather than in a laboratory) using several N. furcifer nests. The details of the study are pretty fascinating, if you’re interested. See the citation below for a link to the paper. It is a scholarly paper, so it may not be easily accessible.
Dynamics of sibling aggression of a cichlid fish in Lake Tanganyika. Satoh, S., Ota, K., Awata, S. et al. Hydrobiologia (2018). https://doi.org/10.1007/s10750-018-3768-8.